Cambodia - Very Venomous Snakes Found - Daboia siamensis

Daboia siamensis ( Eastern Russell's Viper )

Original photo copyright © Dr Julian White

Family: Viperidae

Subfamily: Viperinae

Genus: Daboia

Species: siamensis

Common Names: Eastern Russell's Viper , Daboia , Tic-Polonga , Siamese Russell's Viper , Seven Pacer , Chain Snake

Local Names: Mwe Pwe , Yuan Ban Kui , Souah-chuwah

Region: Southeast Asia + North Asia

Countries: Cambodia, China, Indonesia, Laos, Myanmar, Taiwan, Thailand, Vietnam

Daboia siamensis ( Eastern Russell's Viper ) Original photo copyright © Dr Julian White

Taxonomy and Biology

Adult Length: 1.00 m

General Shape: Medium in length, heavy and stout bodied, dorsoventrally flattened snake with short a tail. Can grow to a maximum of about 1.70 metres. Head is large, flat, bluntly pointed ( snout is bluntly rounded and broad ), broadly triangular and distinct from neck with strongly keeled scales and large nostrils. Canthus is distinct. Eyes are medium to moderately large in size with vertically elliptical pupils. Dorsal scales are strongly keeled ( except a smooth 1st dorsal scale row ). Dorsal scale count ( 25 to 31 ) - 29 ( 27 - 33 ) - ( 21 to 23 ).

Habitat: Frequently encountered in paddy fields and other agricultural land at elevations below 1000 metres, but may be found in a wide variety of terrain including coastal plains, wooded regions and particularly open, rocky, bushy or grassland regions, hills and mountain foothills up to about 2000 metres. More abundant in open lowland plains and avoids dense jungle terrain.

Habits: Nocturnal and most active during early evening. Captures prey by ambush. If disturbed, it tends to hold its ground rather than flee, hisses loudly and assumes a striking position with a lateral S-shaped loop of the neck. If it strikes it does so with force inflicting a deep bite.

Prey: Feeds mainly on rodents, lizards and frogs.

Daboia siamensis ( Eastern Russell's Viper ) Original photo copyright © Dr Wolfgang Wuster

Venom

General: Venom Neurotoxins	Probably not present
General: Venom Myotoxins	Probably not present
General: Venom Procoagulants	Mixture of procoagulants
General: Venom Anticoagulants	Possibly present
General: Venom Haemorrhagins	Zinc metalloproteinase
General: Venom Nephrotoxins	Possibly present
General: Venom Cardiotoxins	Probably not present
General: Venom Necrotoxins	Possibly present
General: Venom Other	Unknown

Daboia siamensis ( Eastern Russell's Viper ) Battanbang, Cambodia Original photo copyright © David Williams

Clinical Effects

General: Dangerousness	Severe envenoming likely, high lethality potential
General: Rate of Envenoming	>80%
General: Untreated Lethality Rate	10-20%
General: Local Effects	Marked local effects; pain, severe swelling, bruising, blistering, necrosis
General: Local Necrosis	Uncommon but can be moderate to severe
General: General Systemic Effects	Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, dizziness, collapse or convulsions
General: Neurotoxic Paralysis	No clinical reports for this species, but related subspecies cause mild flaccid paralysis (ptosis & ophthalmoplegia)
General: Myotoxicity	No case reports for this species, but related subspecies can cause systemic myolysis
General: Coagulopathy & Haemorrhages	Very common, coagulopathy + haemorrhagins causing bleeding is major clinical effect
General: Renal Damage	Common, renal failure is major clinical effect
General: Cardiotoxicity	Rare, usually secondary
General: Other	Shock secondary to fluid shifts due to local tissue injury is possible in severe cases. Anterior pituitary haemorrhage with panhypopituitarism can occur in bites by Burmese Russell's vipers

First Aid

Description:

First aid for bites by Viperid snakes likely to cause significant local injury at the bite site.

Details

1. After ensuring the patient and onlookers have moved out of range of further strikes by the snake, the bitten person should be reassured and persuaded to lie down and remain still. Many will be terrified, fearing sudden death and, in this mood, they may behave irrationally or even hysterically. The basis for reassurance is the fact that many venomous bites do not result in envenoming, the relatively slow progression to severe envenoming (hours following elapid bites, days following viper bites) and the effectiveness of modern medical treatment.

2. The bite wound should not be tampered with in any way. Wiping it once with a damp cloth to remove surface venom is unlikely to do much harm (or good) but the wound must not be massaged.

3. All rings or other jewellery on the bitten limb, especially on fingers, should be removed, as they may act as tourniquets if oedema develops.

4. The bitten limb should be immobilised as effectively as possible using an extemporised splint or sling; if available, crepe bandaging of the splinted limb is an effective form of immobilisation.

5. If there is any impairment of vital functions, such as problems with respiration, airway, circulation, heart function, these must be supported as a priority. In particular, for bites causing flaccid paralysis, including respiratory paralysis, both airway and respiration may be impaired, requiring urgent and prolonged treatment, which may include the mouth to mask (mouth to mouth) technique of expired air transfer. Seek urgent medical attention.

6. Do not use Tourniquets, cut, suck or scarify the wound or apply chemicals or electric shock.

7. Avoid peroral intake, absolutely no alcohol. No sedatives outside hospital. If there will be considerable delay before reaching medical aid, measured in several hours to days, then give clear fluids by mouth to prevent dehydration.

8. If the offending snake has been killed it should be brought with the patient for identification (only relevant in areas where there are more than one naturally occurring venomous snake species), but be careful to avoid touching the head, as even a dead snake can envenom. No attempt should be made to pursue the snake into the undergrowth as this will risk further bites.

9. The snakebite victim should be transported as quickly and as passively as possible to the nearest place where they can be seen by a medically-trained person (health station, dispensary, clinic or hospital). The bitten limb must not be exercised as muscular contraction will promote systemic absorption of venom. If no motor vehicle or boat is available, the patient can be carried on a stretcher or hurdle, on the pillion or crossbar of a bicycle or on someone's back.

10. Most traditional, and many of the more recently fashionable, first aid measures are useless and potentially dangerous. These include local cauterization, incision, excision, amputation, suction by mouth, vacuum pump or syringe, combined incision and suction ("venom-ex" apparatus), injection or instillation of compounds such as potassium permanganate, phenol (carbolic soap) and trypsin, application of electric shocks or ice (cryotherapy), use of traditional herbal, folk and other remedies including the ingestion of emetic plant products and parts of the snake, multiple incisions, tattooing and so on.

Treatment

Treatment Summary: Bites by Russell's vipers cause severe, potentially lethal envenoming, requiring urgent assessment & treatment with IV fluids, IV antivenom and good wound care.

Key Diagnostic Features: Local pain, swelling, blistering, necrosis + coagulopathy, bleeding, renal failure, rarely anterior pituitary haemorrhage with panhypopituitarism.

General Approach to Management: All cases should be treated as urgent & potentially lethal. Rapid assessment & commencement of treatment including appropriate antivenom (if indicated & available) is mandatory. Admit all cases.

Antivenom Therapy: Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.

Antivenoms

1. Antivenom Code: SAsTRC05

Antivenom Name: Russell's Viper Antivenin

Manufacturer: Science Division, Thai Red Cross Society

Phone: ++66-2-252-0161 (up to 0164)

Address: Queen Saovabha Memorial Institute

1871 Rama IV Road

Pathumwan

Bangkok 10330

Country: Thailand

2. Antivenom Code: SAsGPO02

Antivenom Name: Russell's Viper Antivenom

Manufacturer: Thai Government Pharmaceutical Organisation

Phone: ++662-644-8851

Address: 75/1 Rama VI Road,

Ratchathewi

Bangkok 10400,

Country: Thailand

3. Antivenom Code: SAsVRU05

Antivenom Name: Naja siamensis Antivenom

Manufacturer: Venom Research Unit

Address: University of Medicine and Pharmacy

Ho Chi Minh City

217 An Duong Vuong Q5

Country: Vietnam

4. Antivenom Code: SAsPIM01

Antivenom Name: Bivalent

Manufacturer: Pharmaceutical Industries Corporation

Phone: +95-1-566742

+95-1-566750

Address: 192 Kaba Aye Pagoda Road,

Bahan, Yangon,

Country: Myanmar ( Burma )

5. Antivenom Code: SAsPIM03

Antivenom Name: Anti-Viper, Russell's Viper

Manufacturer: Pharmaceutical Industries Corporation

Phone: +95-1-566742

+95-1-566750

Address: 192 Kaba Aye Pagoda Road,

Bahan, Yangon,

Country: Myanmar ( Burma )

Source: Clinical Toxinology Resources